RavenWindow automatically changes transparency with temperature

Windows that change their tint are not new, but this window by RavenBrick does so without any energy use required. The RavenWindow changes its transparency depending on the temperature, so basically if it's hot outside less heat passes through it and if it's cold outside then it becomes more transparent, allowing in more heat from the sun. The implications are obvious – savings in your energy bill as a result of reduced use of your heater or air conditioner. With "America's Greenest Building" commissioning the first commercial installation of the product, it's bound to have a bright future.

The key element in the window is a layer of thermoreflective material between the internal and external layers of glass. When the temperature of that material exceeds the threshold, it becomes reflective, bouncing off at least 90% of the incoming solar energy.

RavenBrick claim that this will cut your energy bills by at least 30%, which is certainly a value not to be sniffed at. Additionally, it requires no effort on behalf of the property owner, other than the effort required to order the windows in the first place.

With the material at the core of the product being "an organic, nontoxic polymer", I can't actually think of a single problem with this product, although the obvious question is how much is it going to cost an average consumer?